I take my larger dog to my groomer when my small dog gets groomed once a month and I know when the time is getting close because I hear the clicking from both dogs' feet.

So once every 4 weeks is perfect for us but you may also want to check with your groomer that she is taking off enough. Once I made it clear to my groomer that I hated the clicking she's been careful to take off enough(but not enough to make Susie bleed or anything) that I don't normally hear excessive clicking until it's close to grooming time again(some clicking is normal).